import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class SQLHelper extends SQLiteOpenHelper {
	
	private final static String DATABASE_NAME = "todo_db";//数据库名
	private final static int DATABASE_VERSION = 1;//数据库版本号
	private final static String TABLE_NAME = "todo_table";//数据库表名
	public final static String FIELD_id = "_id";//
	public final static String FIELD_TEXT = "todo_text";//字段

	public SQLHelper(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		String sql = "CREATE TABLE " + TABLE_NAME + " (" + FIELD_id
				+ " INTEGER primary key autoincrement, " + " " + FIELD_TEXT
				+ " text)";
		db.execSQL(sql);

	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub
		String sql = "DROP TABLE IF EXISTS " + TABLE_NAME;
		db.execSQL(sql);
		onCreate(db);
	}	
	
	
	public Cursor select() {
		SQLiteDatabase db = this.getReadableDatabase();
		Cursor cursor = db
				.query(TABLE_NAME, null, null, null, null, null, null);
		return cursor;
	}

	public long insert(String text) {
		SQLiteDatabase db = this.getWritableDatabase();
		ContentValues cv = new ContentValues();
		cv.put(FIELD_TEXT, text);
		long row = db.insert(TABLE_NAME, null, cv);
		return row;
	}

	public void delete(int id) {
		SQLiteDatabase db = this.getWritableDatabase();
		String where = FIELD_id + " = ?";
		String[] whereValue = { Integer.toString(id) };
		db.delete(TABLE_NAME, where, whereValue);
	}

	public void update(int id, String text) {
		SQLiteDatabase db = this.getWritableDatabase();
		String where = FIELD_id + " = ?";
		String[] whereValue = { Integer.toString(id) };
		ContentValues cv = new ContentValues();
		cv.put(FIELD_TEXT, text);
		db.update(TABLE_NAME, cv, where, whereValue);
	}

}